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posterior side is more convex; bounding the anterior 
side is a slight ridge marked near the edge with bent strie 
and projecting a little beyond it; the shell is so thin 
that it cannot be separated from the stone so as to shew 
the hinge, although it is so well preserved that the 
cartilage remains. 
From Kelloways, by favour of Mr. Salmon, and the 
Rev. Mr. Steinhauer. The middle figure is from a cast 
in yellowish carbonate of Lime, somewhat transparent, 
from the same place. 
ISOCARDIA rostrata. 
TAB. CCXCV.— Fig. 3. 
Srec. Cuar. Deltoid, ventricose ; anterior side pro- 
duced, pointed ; posterior depressed, rounded. 
Remarxazry ventricose, especially towards the front, 
which is rather straight and terminated at the anterior 
side by a short beak. About the size of a large hazle 
nut. 
‘Two or three specimens which are only casts of this 
Isocardia in Limestone, were sent me with some other 
shells from the Coteswold Hill in Gloucestershire, by 
Mr. Taylor, in the year 1816. I have waited in vain 
thus long (5 years) for more perfect specimens, and 
therefore figure these such as they are, they may serve 
to Identify the species. 
ISOCARDIA sulcata. 
TAB. CCXCV.— Fig. 4. 
Spec. Cuar. Orbicular, deeper than wide, longi- 
tudinally sulcated, pearly ; beaks remote. 
A pretty little pearly shell, the beaks are much incurved 
with a considerable cordate cavity beneath them; the 
sulci are numerous and broad. 
Only a single individual has been found in the canal 
at Islington, in the London Clay; itis much impregnated 
with Pyrites, so I fear will soon be lost, but I am not 
willing it should be quite forgotten. 
